Modbus Registers
Table of Legacy Dataset Common Registers
The main information needed for remote supervision of a ComPact NSX, ComPact NS, MasterPact NT/NW, or MasterPact MTZ circuit breaker is contained in the table of common registers starting at register 12000.
This compact table of 114 registers can be read with a single Modbus request.
It contains the following information:
-
Circuit breaker status
-
Tripping causes
-
Real-time values of main measurements: current, voltage, power, energy, total harmonic distortion
The content of this table of registers is detailed in Legacy Dataset Common Registers.
Use of these common registers is highly recommended to optimize response times and simplify the use of data.
Table Format
Register tables have the following columns:
|
Address |
Register |
RW |
Unit |
Type |
Range |
A/E |
A/E/P/H |
X |
Description |
|---|---|---|---|---|---|---|---|---|---|
-
Address: a 16-bit register address in hexadecimal. The address is the data used in the Modbus frame.
-
Register: a 16-bit register number in decimal (register = address + 1).
-
RW: register read-write status
-
R: the register can be read by using Modbus functions
-
W: the register can be written by using Modbus functions
-
RW: the register can be read and written by using Modbus functions
-
RC: the register can be read by using the command interface
-
WC: the register can be written by using the command interface
-
-
Unit: the unit the information is expressed in.
-
Type: the encoding data type (see data type description below).
-
Range: the permitted values for this variable, usually a subset of what the format allows.
-
A/E: types of ComPact NSX MicroLogic trip unit for which the register is available.
-
Type A (Ammeter): current measurements
-
Type E (Energy): current, voltage, power, and energy measurements
-
-
A/E/P/H: types of MasterPact NT/NW and ComPact NS MicroLogic trip unit for which the register is available.
-
Type A (Ammeter): current measurements
-
Type E (Energy): current, voltage, power, and energy measurements
-
Type P (Power): current, voltage, power, energy measurements, and advanced protection
-
Type H (Harmonics): current, voltage, power, energy, energy quality measurements, and advanced protection
-
-
X: register available in the MicroLogic X control unit for MasterPact MTZ circuit breakers when the Modbus legacy dataset Digital Module is purchased and installed on the MicroLogic X control unit.
-
Description: provides information about the register and restrictions that apply.
Data Types
|
Data Types |
Description |
Range |
|---|---|---|
|
INT16U |
16-bit unsigned integer |
0 to 65535 |
|
INT16 |
16-bit signed integer |
-32768 to +32767 |
|
INT32U |
32-bit unsigned integer |
0 to 4 294 967 295 |
|
INT32 |
32-bit signed integer |
-2 147 483 648 to +2 147 483 647 |
Big-Endian Format
INT32 and INT32U variables are stored in big-endian format: the most significant register is transmitted first and the least significant register is transmitted at last place.
INT32 and INT32U variables are made of INT16U variables.
The formulas to calculate the decimal value of these variables are:
-
INT32: (0-bit31)x231 + bit30x230 + bit29x229 + ...bit1x21 + bit0x20
-
INT32U: bit31x231 + bit30x230 + bit29x229 + ...bit1x21 + bit0x20
Example:
The reactive energy in the legacy dataset is an INT32 variable coded in registers 12052 to 12053.
If the values in the registers are:
-
register 12052 = 0xFFF2 = 0x8000 + 0x7FF2 or 32754
-
register 12053 = 0xA96E or 43374 as INT16U variable and -10606 as INT16 variable (use the INT16U value to calculate the value of the reactive energy).
Then the reactive energy is equal to (0-1)x231 + 32754x216 + 43374x20 = -874130 kVARh.